An Interorganizational Business Process (IOBP) is an organized group of related activities carried out by multiple organizations to accomplish a common business goal. A consequence of this is that business process modeling and design used inside an organization have to be enhanced and extended to cope with interorganizational business relationships. Modeling business processes that span multiple organizations involves new challenges, mainly the ability to cope with autonomy, privacy, heterogeneity, and the support for coordination trough mutual agreements. As a contribution to this area, this paper presents a metamodel that captures a wide range of IOBP elements.